Antimicrobial compositions are generally added to various kinds of industrial water based fluids to reduce or inhibit the growth of microorganisms. In particular, a wide variety of industrial water based fluids such as metal-working fluids, latex paints, water based hydraulic fluids, require antimicrobial compositions to control the growth microorganisms which eventually render the fluids rancid.
One of the problems often associated with water based fluids is the susceptibility of the fluid to the infestation and growth of various microorganisms such as bacteria and fungi (which particularly feed on the organic components thereof). The presence and buildup of such microorganisms can often lead to interference of mechanical operations as a result of the clogging of filters, buildup of slime and sludge, development of odors, rust, emulsion instability, reduced tool life and poor finish. Furthermore, where the workers' hands necessarily come in contact with these deteriorated fluids, usually containing finely divided sharp metal cuttings, serious problems of dermatitis may arise. These and other such similar problems have resulted in the continuing need for better antimicrobial additives for industrial water based fluids. Much effort has been devoted in recent years to controlling this problem; however, it continues to be a major annoyance which costs industry many millions of dollars each year.
Antimicrobial agents constitute an important ingredient of industrial fluids which are commonly depleted faster than the other components of the fluids. Quite often, additional antimicrobial agents must be added to the industrial water based fluid at periodic intervals in order to compensate for their loss from the fluid after continuous use.
Preservatives are removed from the fluid after interacting with the microbes to bring about their inhibition or death. The greater the microbial population, the more quickly they are lost from the system. Thus, the concentration of any preservative declines with time and may be reduced to subinhibitory levels in only a few days.
A number of suggestions have been made for inhibiting the growth of bacteria in aqueous fluids such as those described in U.S. Pat. Nos. 4,172,140, 3,951,830, 3,799,876, 3,515,671, and 2,976,244. The use of various formaldehyde preservatives for metalworking fluids including monomethylol dimethyl hydantoin and dimethylol dimethyl hydantoin has also been proposed (see Bennett, E. O., Int. Biodetn. Bull. 9: 95-100 (1973) and Maeda et al, Agr. Biol. Chem., 40: 1111-2222 (1976)).
Gray and Wilkinson in J. Gen. Microbiol., 39: 385-399 (1965) and J. App. Bact., 28: 153-164 (1965) describe the action of the ethylenediaminetetraacetic acid (EDTA) on some bacteria. The effectiveness of such chelating agents as EDTA along for bacterial control in aqueous systems is disputed as evidenced by U.S. Pat. Nos. 3,240,701, 3,408,843, and 3,591,679.
The antimicrobial compositions used in industrial water based fluids seem to suffer from one or more disadvantages including high cost, unacceptable toxicity or low degree of effectiveness at the present state of the art.
The present invention provides agents which when combined with antimicrobial agents are effective to potentiate the activity of the antimicrobial agent in controlling the growth of microorganisms in industrial water based fluids. Hence, less antimicrobial agent is required to produce the same antimicrobial effect as compared to using the antimicrobial agent alone.